Conventionally, as one of methods for decorating the surface of synthetic resin molded articles, a method (insert molding) has been known in which a resin film which has been preliminarily decorated is placed in a mold, and a synthetic resin is injected into the mold so that the decorated resin film is unified with the synthetic resin injection-molded body. Further, the use of an ultraviolet curing ink jet ink in decorating a resin film for use in insert molding has been proposed (for example, Patent Literature 1 to 3).
When a resin film decorated using an ultraviolet curing ink jet ink is used in insert molding, there is a problem, for example, in that the decorative layer cannot withstand stretching during the preforming or injection molding processing, so that a crack is caused in the decorative layer. For solving the problem, for example, Patent Literature 4 has a description that, by using a resin film decorated using an ultraviolet curing ink jet ink containing N-vinylcaprolactam, dicyclopentenyloxyethyl acrylate, and bisphenol A epoxy (meth)acrylate and/or urethane (meth)acrylate, an insert molded article having high image quality can be obtained. However, the Patent Literature 4 has a problem in that a defect, such as a crack, is likely to be caused in the decorative film after the preforming.